We have inherited an old bumpy (lethal for kids to fall on) porous tarmac tennis court and the cost of replacement with astroturf is too expensive. Therefore I’d like to replace with grass. Rather than completely dig up and re-seed, is it an option to simply put topsoil over the court and if so, how much is needed for grass to grow?
This could be done with a digger quite quickly and topsoil brought in to replace it. You might even find a home for the hardcore stone if somebody is making a driveway or paved area, for instance.
Putting a layer of top soil down on tarmac will leave the grass very likely to dry out in summer and a layer of at least 15cm of top soil would be needed, which will probably leave the tennic court area too high compared to surrounding area.